diff --git a/core/src/cache.rs b/core/src/cache.rs
index 28b787ff..1a58bdc0 100644
--- a/core/src/cache.rs
+++ b/core/src/cache.rs
@@ -1,8 +1,11 @@
-use std::path::PathBuf;
-use std::io::Read;
+use std::fs;
 use std::fs::File;
+use std::io;
+use std::io::Read;
+use std::path::Path;
+use std::path::PathBuf;
 
-use util::{FileId, mkdir_existing};
+use util::FileId;
 use authentication::Credentials;
 
 #[derive(Clone)]
@@ -11,6 +14,16 @@ pub struct Cache {
     use_audio_cache: bool,
 }
 
+fn mkdir_existing(path: &Path) -> io::Result<()> {
+    fs::create_dir(path).or_else(|err| {
+        if err.kind() == io::ErrorKind::AlreadyExists {
+            Ok(())
+        } else {
+            Err(err)
+        }
+    })
+}
+
 impl Cache {
     pub fn new(location: PathBuf, use_audio_cache: bool) -> Cache {
         mkdir_existing(&location).unwrap();
diff --git a/core/src/util/mod.rs b/core/src/util/mod.rs
index f9304f0b..f96a5431 100644
--- a/core/src/util/mod.rs
+++ b/core/src/util/mod.rs
@@ -2,11 +2,8 @@ use num_bigint::BigUint;
 use num_traits::{Zero, One};
 use num_integer::Integer;
 use rand::{Rng, Rand};
-use std::io;
 use std::mem;
 use std::ops::{Mul, Rem, Shr};
-use std::fs;
-use std::path::Path;
 use std::process::Command;
 
 mod int128;
@@ -21,16 +18,6 @@ pub fn rand_vec<G: Rng, R: Rand>(rng: &mut G, size: usize) -> Vec<R> {
     rng.gen_iter().take(size).collect()
 }
 
-pub fn mkdir_existing(path: &Path) -> io::Result<()> {
-    fs::create_dir(path).or_else(|err| {
-        if err.kind() == io::ErrorKind::AlreadyExists {
-            Ok(())
-        } else {
-            Err(err)
-        }
-    })
-}
-
 pub fn run_program(program: &str) {
     info!("Running {}", program);
     let mut v: Vec<&str> = program.split_whitespace().collect();